The long-term objective of this proposal is to sustain the Adolescent Medicine Trials Network (ATN) under a cooperative agreement. This network will have the capacity for developing and conducting selected behavioral, community-based translational, prophylactic, therapeutic, and vaccine trials based on and adding to the information developed through the Adolescent Medicine HIV/AIDS Network (1994-2001) and the current Adolescent Trials Network for HIV/AIDS Interventions (2001-2006). The primary mission of the ATN for HIV/AIDS Interventions will be to conduct research, both independently and in collaboration with existing research networks and individual investigators, in HIV-infected and HIV-at-risk pre-adolescents, adolescents, and young adults up to age 25 years. The ATN will bring expertise and resources to collaborative protocol development that will ensure feasible and acceptable study design as well as experience in recruiting and retaining this unique population. This network will design, develop, and conduct multiple common clinical trials as well as pertinent formative and translational research studies collaboratively or independently when needed. The ATN is the first clinical research infrastructure to address the particular challenges and unique clinical management demands of HIV-infected adolescents and the prevention needs of at-risk youth through common protocols. All HIV-infected youth are faced with social and physical developmental challenges of puberty that make coming to terms with chronic illness, complex drug regimens, and disclosure to peers an intensely more complicated endeavor. An estimated 11.8 million young people aged 15 to 24 are living with HIV/AIDS worldwide and each day another 6,000 young people are newly infected. In the US, the rate in youth remains among the highest. The ATN's current agenda needs to be sustained and expanded to meet the emerging needs of this population. Primary prevention studies will focus on efforts to interrupt HIV transmission in uninfected populations. Secondary prevention studies examine ways to preserve health in HIV-infected populations. Tertiary prevention studies are needed to restore ill HIV-positive youth to full or better function. [unreadable] [unreadable]